Method of surface finishing a workpiece

ABSTRACT

A METHOD AND MEANS FOR SURFACE FINISHING A WORKPIECE. THE METHOD INVOLVES ROTATION OF A WORKPIECE IMMERSED IN A BED OF FINISHING MEDIA OF FLUIDIZED CHARACTER AND SIMULTANEOUSLY EFFECTING RELATIVE BODILY MOVEMENT OF THE WORKPIECE AND THE BED IN ONE OR MORE DIRECTIONS. THE MEANS UTILIZED TO PRACTICE THE METHOD FLUIDIZES THE BED OF MEDIA, SWINGS THE WORKPIECE LATERALLY IN THE BED OR VARIES THE DEPTH OF IMMERSION IN THE BED, OR BOTH, AND MAY PERIODICALLY REVERSE THE DIRECTION OF ROTATION OF THE WORKPIECE.

March 2, 1971 D, E, HAMBRIGHT 3,566,552

METHOD OF SURFACE FINISHING A WORKPIECE Original Filed May 18, 1967 3 Sheets-Sheet 1 INVENTOR. DUANE E HAMBR/GH T v m m 'ATTORNEY March 197 D. E. HAMBRIGHT METHOD OF SURFACE FINISHING A WORKPIECE Original Filed May 18, 1957 3 Sheets-$heet 5 I N VENTOR. DU/l/VE ,5. HAMBR/GHT 5 ATTORNEY United States Patent 01 fee 3,566,552 Patented Mar. 2, 1971 3,566,552 METHOD OF SURFACE FINISHING A WORKPIECE Duane E. Hambright, Colon, Mich, assignor to Sutton Tool Company, Sturgis, Mich. Original application May 18, 1967, Ser. No. 639,507, now Patent No. 3,516,203, dated June 23, 1970. Divided and this application July 7, 1969, Ser. No. 851,530

Int. Cl. B241) 1/00 US. Cl. 51317 7 Claims ABSTRACT OF THE DISCLOSURE This application is a division of my application Ser. No. 639,507, filed May 18, 1967, now Pat. No. 3,516,203, dated June 23, 1970.

This invention relates to method of surface finishing a workpiece.

The surface finishing of workpieces, such as metal parts which are required to be produced within close dimensional and finish tolerance, and the deburring of metal parts has been practiced widely, and various methods and mechanisms have been devised for such services. These prior methods and mechanisms commonly en: tail the movement of one or more workpieces or parts within a body of abrasive or surface finishing media, as by rotation of the work within the media. Such prior mechanisms and methods have been of various types which have heretofore had various limitations. One of the most critical limitations of prior methods and apparatus has been inability to satisfactorily and completely surface finish highly complex mechanical structures, having multiple grooves and openings, such as slotted rotors which mount the blades of a jet engine. Prior mechanisms have tended to produce channels within the media of abrasive of finishing material which reduced their effectiveness, or have tended to produce unequal finishing action at different parts of the workpiece. Another limitation of prior devices has been that some of the sharp edges or corners of a workpiece are worked, re-shaped or finished more than others. Thus, it has been common to require final hand-buffing and polishing of workpieces which must be accurate in order to effect deburring and radiusing of sharp corners with the uniformity required to insure against the occurrence in the workpiece of flaws of a nature which could lead to failure of the workpiece during use thereof. Such hand-buffing and polishing of a workpiece, such as a peripherally slotted blademounting jet engine rotor, may take hours of work and does not insure desired uniformity of radiusing at all corners and edges. It is not uncommon for such handbutfing to require 6 to 8 hours for a rotor of 12 inch diameter, and a longer period for rotors of larger sizes.

It is the primary object of this invention to provide a method which can accomplish within a few minutes at most, the deburring and radiusing of corners and edges of a workpiece with greater uniformity than has been possible heretofore, and with requisite quality of the finished workpiece and assurance that all edges of the workpiece, regardless of their location, and including edges at re-entrant grooves and like locations heretofore diflicult of access, are properly treated or radiused.

A further object is to provide a method of surface finishing metal parts by immersing thereof within a fluidized media in which the workpiece is rotated and is oscillated or moved relative to the media so as to expose the workpiece to media at different levels or at different lateral portions of the media receptacle or container, or both.

Other objects will be apparent from the following specification:

In the drawings:

FIG. 1 is a view of the device in side elevation.

FIG. 2 is a fragmentary detail sectional view taken on line 24 of FIG. 1.

'FIG. 3 is a top plan view of the device.

FIG. 4 is a top plan view of the device with parts broken away to illustrate one position of the work carrier spindle in a media container.

FIG. 5 is a view similar to FIG. 4, but illustrating a work carrier spindle in a different lateral position in the media container.

FIG. 6 is a side view of the device illustrating controls therefor schematically.

Referring to the drawings, which illustrate a preferred embodiment of the invention, the numeral 410 designates a base of a machine frame, which base supports two rigid uprights or posts 12 at opposite sides thereof and intermediate the front and rear edges thereof. Each post carries a lower front vertical guide plate 14 and an upper rear vertical guide plate 16 projecting inwardly therefrom. Alternatively, the uprights may constitute channel members or members of H section.

A receptacle, tank or container 20 open at its top constitutes means for confining and containing a surface treating media of any desired type. Thus, tank 20 may contain a wet abrasive slurry such as aluminum oxide, silicon carbide or a natural abrasive, or it may contain a. dry bufiing media, such as rouge. The tank 20 has two lower wheels or rollers 22 journaled upon brackets 24 preferably projecting from the bottom of the tank 20 at opposite sides of the rear portion thereof and each engagable with one of the lower front vertical guide plates 14. Tank 20 also carries upper wheels or rollers 26 journaled on brackets 28 carried by the upper rear portions of the tank 20 and each engagable with one of the upper rear vertical guide plates 16. Lateral projections 30 are carried by opposite sides of the front portion of the tank 20, and each has pivotally connected thereto the piston rod 32 of a fluid pressure actuated extensible power member having a cylinder 34 which is fixedly anchored at its lower end at 36 to the base plate 10. The parts are so constructed and arranged that the fluid pressure members 32, 34 support the front of the tank and control its elevation while the rollers 22 and 26 position the rear portion of the tank 20 so as to maintain the tank 20 in an upright position at all times and regardless of the elevation at which the tank is supported by the fluid pressure members 32, 34.

The bottom '38 of the tank 20 preferably mounts a motor 40 having a horizontal rotating shaft 42 upon which is mounted eccentrically a weight member 44. The motor 40 may be an electric motor or a fluid pressure motor, and in either case has flexible connections accommodating the vertical reciprocation of the tank during usage. It will be apparent that the rotation of the eccentrically mounted weight 44 by the motor shaft 42 produces vi bration, which vibration is transmitted to the tank 20 and the media contained therein. In the event a wet slurry of abrasive or metal treating media is provided, the tank will be provided with a liquid inlet 46 and a liquid outlet 48 connected by suitable flexible liquid lines to a liquid source and a discharge point, so that water or a detergent solution may be circulated through the media. Suitable filter means (not shown) are provided to insure retention of the media while liquid circulates therethrough.

A rigid member 50 fixedly interconnects the upper ends of the uprights 12 and cooperates therewith and with base to provide the frame of the device. If desired, mem ber 50 may form a continuation of the upper rear guide plates 16. Frame member 50 mounts a pair of vertically spaced brackets or journals 52 which support or otherwise mount in selected vertical position a shaft 54 which projects above the upper ends of the uprights 12 and the upper frame member 50. A rigid horizontal head unit 56 includes a bottom plate or member 58 which mounts an open ended sleeve or cylinder 60 having a snug rotatable fit upon the upper end of shaft 54, with its lower end projecting below the plate 58 and bearing upon the upper bracket or journal 52 to position the head unit 56 vertically clear of the frame parts 12 and 50. The head unit includes suitable reinforcing parts and an upright plate portion 62 at one side therof upon which is fixedly secured an electric motor 64, such as a motor with a geared speed reducing head. Motor 64 has an upwardly projecting motor shaft 66 mounting a pulley or sprocket 68, as best seen in FIG. 3. The motor 64 is speced from the shaft 54 and from the frame parts 12 and 50.

In spaced relation to motor 64 and shaft 54, the head unit 56 is provided with means for journaling an upright spindle 70, which means may include an apertured bridge structure 72 of rigid characted mounted upon the head. Plate 58 and bridge 72 each has an opening through which the spindle 70 extends. Upper bearing means 74 and lower means 76 may be adjustably mounted upon the head 56 to journal the spindle 70 in selected position and angular relation to the head 56. At its upper end, the spindle 70 may carry a pulley or sprocket 78 cooperating with the pulley or sprocket 68 on the motor shaft 66 to carry drive transmission means 80, such as a belt or a chain. The lower end of the drive spindle Will be provided with suitable collet or chuck means 82, or other work holder by which one or more wrokpieces 84 may be detachably mounted. It will be understood that while only one spindle mount and one spindle is shown in the construction illustrated, two or more spindles and spindle mounts may be provided. Also, it will be understood that the work holding means 82 may be constructed to mount a plurality of workpieces, rather than a single workpiece.

Means are provided in the device for laterally shifting I or swinging the head 56 about shaft 54. In the conconstruction shown, these means constitute an extensible and contractible member anchored at one end at 86 to the frame of the device, as at plate 50, at a point spaced from shaft 54, and anchored at its opposite end at 88 to head 56 at a point to provide a triangular relation or orientation between the two anchor points 86, 88 and the shaft 54. The extensible and contractible unit may be of any character desired, but is here shown as a fluid pressure actuated member having a cylinder 90 pivoted to one of the anchors 86, 88 and a piston rod 92 pivoted to the other anchor. The two fluid pressure operated units 32434 and 9092 are preferably operable by compressed air, although they may constitute hydraulic units if desired.

An illustrative control for the operation of the mechanism is illustrated in FIG. 6, wherein a source of compressed air 94 is connected by a line 96 to a control valve 98 which is of the electrically actuated type, such as a solenoid valve. Valve 98 is controlled by a limit switch 100, or reversing switch. As shown in FIG. 6, the switch 100 may have an actuator part 102 which is positioned between circumferentially spaced stops or abutment members 104 carried by the shaft 54 in cases where the shaft 54 is journaled or rotates in brackets or Cit journals 52. Lines 106 and 108 connect the valve 98 with opposite ends of the cylinder of the double-acting power member 90, 92. The valve 98 is so constructed that, in one setting of the actuator 102 of the limit switch compressed air will flow through line 106 to the cylinder 90 and the opposite end of said cylinder will be vented through the line 108 and the valve to a valve bleed port 110. In the opposite setting of the valve 98 and the switch actuator part 102, compressed air will flow to the cylinder 90 through line 108, and air will be evacuated from the opposite ends of the cylinder 90 through the line 106 to the bleed port 110. By this means, the head 56 will be swung about the shaft 54 through a selected are or path, as between the positions shown in FIGS. 4 and 5, so that the spindle 70 and the work 84 will be moved laterally in the media in the tank 20. It will be apparent that the amplitude of swinging movement of head 56 will depend upon the spacing of the stops or abutments 104, which stops or abutments will preferably be mounted adjustably to accommodate variations in spacing therebe tween as desired.

Means may be provided for varying and controlling the depth of immersion of work in media in the tank 20, as by operation of the fluid pressure actuated members 32, 34 to raise and lower tank 20. As here shown, such means may include stops or abutments 112 and 114 mounted upon the tank 20 at selected positions or elevations, which may be adjustable if desired. A limit switch or reversing switch 116 is carried by a fixed part of the frame, such as an upright 12, and has a part 118 constituting a switch actuator engageable by the abutments 112 and 114. The switch 116 controls a valve 120, such as a solenoid valve, which is connected to the source 94 of compressed air by a line 122 and is connected by a line 124 with the lower ends of the cylinders 34 of the fluid pressure members 32, 34. The fluid pressure members 32, 34 are preferably of the single action type, and the valve 120 has a bleed port 126. The arrangement is such that during descending movement of the tank 20, as illustrated in FIG. 6, air will bleed from the cylinders 34 and will discharge at the outlet 126 of valve 120. As soon as the upper abutment 112 engages and moves the switch actuator 1 18, the setting of the valve 120 is reversed to establish communication between conduits 122 and 124 whereupon air will be supplied to the cylinders 34 and will produce upward movement of the tank 20 to the dotted line position shown in FIG. 6, at which the lower abutment 114 will engage and move the switch actuator and reverse the setting of the valve 120 to the position shown in FIG. 6, to again commence lowering of the tank. It will be understood that suitable means (not shown) may be provided by which the operator of the device may manually control the position of the tank 20, as by lowering the same to an extent greater than occurs in normal operation under control of switch 116 and stop 112 and sufficient to free the workpiece 84 from the media within the tank as for the purpose of unloading and reloading workpieces relative to the spindle 70.

Motor 64 will preferably be a reversible motor. Suitable means for periodically reversing the motor, such as a time controlled reversing switch .128, may be provided to periodically reverse the direction of rotation of the workpiece within the media in the tank 20. The time interval at which reversals occur will preferably be short as compared to the time during which the surface finishing of a given part within the machine continues. Thus, if the finishing of a part requires 4 or 5 mniutes operation of the machine, the reversing switch may be set to reverse at 1 minute or /2 minute or other intervals, so that several reversals occur during the finishing action upon a given part.

By the use of the device described above, the surface finishing of one or more workpieces may proceed according to the following method: the workpiece is immersed in a bed of fluidized finishing media which may be either wet or dry, the fiuidizing of which accommodates freedom of relative movement between the immersed workpiece and the media. The fluidizing of the media is accomplished either by the circulation of liquid through the media, preferably in an upward flow, or by the vibration of the media containing tank, or by both actions. The workpiece is rotated while immersed in the media and, if desired, the direction of rotation of the workpiece in the media may be reversed periodically. The wOrkpiece is shifted laterally within the media while it is being rotated, such shifting being oscillatory; that is, back and forth in the media. The method also entails periodic relative vertical oscillation of the workpiece and the media, so that the workpiece rotates within the media at varying depths or strata thereof.

It will be understood that the steps practiced in the method may be selected according to the requirements of the finishing operation to be performed. In one variation of the method the workpiece may be rotated in one direction only while it is being swung laterally in the media and while relative vertical reciprocation of the workpiece and the media occurs. In another variation of the method periodic reversing rotation of the workpiece and lateral swinging thereof in the media may occur without the step of vertical variation of the relative positions of media and workpiece. Still another variation of the method entails reversible rotation of a workpiece in a media accompanied by a vertical relative movement of media and workpiece.

In all methods, the principle of operation entails continuously varying the relationship of the workpiece and the media so as to avoid channeling of the media which otherwise may occur incident to functioning of a surface finishing machine involving only the rotation of a workpiece while immersed within a media. Further, the method insures that all surfaces, including recessed or re-entrant surfaces, are exposed to the surface treating operation regardless of their location. Still another important consideration is that all sharp edges or corners, regardless of their location upon a workpiece, are similarly and substantially equally exposed to the action of the media so that radiusing of such sharp edges or corners will be substantially uniform throughout, and the uniformity thereof will far exceed that achieveable by hand operation. The amount of edge treatment or radiusing which is accomplished depends upon various factors such as the hardness of the material of the workpiece, the type of media utilized, the speed of rotation, and the time during which the workpiece is treated. Thus, it is possible to control the aforementioned variables for workpieces of different metals so as to assure uniformity of radiusing of sharp edges and corners thereof through a selected range, such as a range in which the radius formed may be as small as .001 inch or as large as .03 inch. It will be understood that this range is cited as illustrative, and is not intended to be limiting.

The manner in which the method aforementioned is performed by the apparatus described, is as follows: The rotation of the workpiece results from rotation of the spindle 70 by the motor 64 through the drive transmission parts 66, 68, 78 and 80. Periodic reversal of the direction of rotation of the workpiece is accomplished by the functioning of the time controlled reversing switch 128 which controls the motor 64. The lateral oscillation of the workpiece within the media in the tank is accomplished by periodic reversing actuation of the fluid pressure member 90, 92 by the valve 98 under the control of the switch 100 for the purpose of swinging the head 56 about the axis of the shaft 54, which head carries within the drive motor 64, the spindle 70 and the workpiece. The depth of immersion of the workpiece in the media in the tank 20 is controlled by successive reversing operation of the fluid pressure power members '32, 34, with variation of that depth being controlled by periodic reversal of the valve 120 under the control of the switch 116 responsive to and engaged by abutments at different elevations upon the tank.

While the preferred embodiment of the invention has been illustrated and described, it will be understood that changes from that embodiment may be made which fall within the scope of the appended claims without departing from the spirit and essence of the invention.

I claim:

1. The method of surface finishing a. workpiece consisting of the steps of:

rotating a workpiece while immersed in a bed of surface finishing media,

agitating said bed of media to maintain uniform continuity of the bed, and

moving one of said media and workpiece relative to the other simulteneously with said work rotating and bed agitating steps.

2. The method of surface finishing a workpiece as defined in claim 1, wherein:

said last named step consists of continuously reciprocat ing and work piece laterally in said media.

3. The method of surface finishing a workpiece as defined in claim 1 wherein:

said last named step consists of progressively varying the depth of immersion of said workpiece in said media. 4. The method of surface finishing a workpiece as defined in claim 1, wherein said agitation consists of vibrating said bed of media.

5. The method of surface finishing a workpiece as defined in claim 1, wherein:

said last named step consists of continuously varying the lateral position of said workpiece in said bed of media and simultaneously varying the depth of immersion of said work piece in said bed of media.

6. The method of surface finishing a work piece as defined in claim 1, and

periodically reversing the direction of rotation of said workpiece in said media.

7. The method of surface finishing a workpiece as defined in claim 1, wherein:

said last named step consists of effecting relative movement of said immersed rotating workpiece and said media back and forth in a selected path between predetermined limits.

References Cited UNITED STATES PATENTS 1,73 3,192 10/ 1929 Haber. 2,218,353 10/ 1940 Gruenberg 51-7 2,425,640 8/1947 Pruitt et al 51-7 2,494,733 1/1950 Whitehead 51-3 17X 2,664,676 1/ 1954 Cuppers 51-7 2,684,562 7/1954 Balz et a1. 51-3 17 2,700,254 1/ 1955 Kinker et a1. 51-7X 2,735,232 2/ 1956 Simjian 517 2,899,777 8/1959 Davidson 513 17X LESTER M. SWINGLE, Primary Examiner 

